1. Field of the Invention
The field of art to which the invention pertains is solidbed adsorptive separation. Specifically, it relates to an improved process for separating sterols from sterol-containing material found occurring in nature. The improved process utilizes an adsorbent and desorbent particularly adapted, in combination, to separate the sterols without deactivating the adsorbent.
2. Description of the Prior Art
It is known in the art to separate sterols from tall oil fractions, e.g., pitch, and cholesterol from wool fat, etc. U.S. Pat. No. 4,664,807 discloses the method of isolating cholesterol from a source of sterol-containing material in a column packed with alumina, magnesium silicate (Florisil) or silica gel and eluting the cholesterol with a liquid such as heptane-acetone 19:1 (v:v), toluene; acetone 29:1 (v:v), toluene heptane-n-butyl acetate 5:1 (v:v) or heptane-toluene-acetone 70:1:9. However, the acids in tall oil will rapidly deactivate the Florisil and silica adsorbents.
Tall oil contains several sterols, e.g., .alpha.-and .beta.-sitosterol, the latter of which is especially used in cosmetics, such as moisturizing cream, lipstick, etc., as an emulsifier, viscosity regulator, emulsion stabilizer and skin softener. Phytosterol was separated from sulfate soap, a by-product of tall oil manufacture, by column chromatography on alumina by the Russians, Nekrasova and Kaganovich and Associates. Cholesterol has been adsorbed onto activated charcoal and steady state reached by W. S. Dorson et al., Trans, Am. Soc., Artif., Intern. Organs, 25, pp 77-80, 1979.